XIV DIOTOCARDIA — RHIPIDOGLOSSA 409 



surface spirally Urate, scaly, spinose, umbilicate, peristome con- 

 tinuous. Single genus, JDelpMnula. (iv.) Umhoniinae. — Eyes 

 pedunculate, left tentacle attached to a frontal appendage, mantle 

 reflected over edge of aperture, lateral teeth 6 on each side ; 

 shell polished, peristome incomplete, umbilicus generally closed 

 by a callosity. Principal genera : Umbonium, Uthalia, Isanda, 

 Camitia, Umhonella^ Chrysostoma. 



Fam. 6. Turhinidae. — Epipodial line with slender cirrhi, snout 

 broad, short, eyes pedunculate at outer base of tentacles, a frontal 

 veil between tentacles ; shell turbinate, solid, aperture continuous, 

 operculum solid, calcareous, usually paucispiral, convex exteriorly 



(Fig. 182, p. 268). Silurian . (i.) Phasianellinae. — ^hQ\\ 



bulimoid, polished, not nacreous, coloured in patterns, aperture 

 oval. Single genus, Phasianella (Fig. 271). (ii.) Turhininae. — 

 Shell very solid, nacreous within, aperture circular or long oval. 

 Principal genera, Turho^ whorls rounded above and below, spines, 

 if present, becoming more prominent with age, operculum smooth 

 orgranulose, nucleus sub-central; subg. Callopoma^ Ninella^ Mar- 

 morostoma^ Sarmaticus, Prisogaster ; Astralium, whorls flattened 

 above and below, spines, if present, becoming less prominent with 

 age, operculum oblong, often excavated at centre, last whorl large, 

 nucleus marginal or sub-marginal ; subg. Lithopoma^ Imperator^ 

 G-uildfordia^ Bolma^ Cyclocantha^ Uvwnilla^ 

 Cookia^Pomaulax^Pachypoma. (iii.) Cyelo- 

 nematinae. — Shell nacreous, umbilicate, 

 operculum conical outside, whorls scalari- 

 form. Principal genera : Cyclonema^ Hori- 

 ostoma (?), Amherleya (Silurian to Lias), 

 (iv.) Leptothyrinae. — Shell small, sr.lid, de- 

 pressed, operculum nearly flat, nucleus sub- 

 central. Genera: Leptothyra^ OoUonia (?). 



Fam. 7. Neritopsidae. — Tentacles wide 

 apart, long, eyes on short peduncles at the 

 outer base; shell solid, neritif orm or naticoid, 

 aperture semi-lunar or oval; operculum 

 (Figf. 183, p. 269) thick, calcareous, non- ^ ^^^ „^ . 



^ . ^ ' ^. / . . P ¥iG. 211.— Phasianella aus- 



spiral, exterior face smooth, interior race traits Gmei., Australia, 

 divided into two unequal parts, with abroad 



median appendage. Devonian . Principal genera: Neri- 



topsis (one recent species), JVaticopsis (Devonian to Miocene). 



